<!doctype html>
<html>

<head>
    <meta charset="utf-8">
    <title>公众号：Python自动化办公社区</title>
    <style type="text/css">
        body {
            background: black;
            padding: 0;
            margin: 0;
            overflow: hidden
        }

        .header {
            margin: 0 auto;
            width: 100%;
            height: 100%;
            background-color: #000;
            position: relative;
        }
    </style>
</head>

<body>
    <div class="header"><canvas id="canvas"></canvas></div>
    <script>
        var canvas = document.getElementById('canvas'),
            ctx = canvas.getContext('2d'),
            w = canvas.width = window.innerWidth,
            h = canvas.height = window.innerHeight,
            hue = 217,
            stars = [],
            count = 0,
            maxStars = 3000;//星星数量
        var canvas2 = document.createElement('canvas'),
            ctx2 = canvas2.getContext('2d');
        canvas2.width = 100;
        canvas2.height = 100;
        var half = canvas2.width / 2,
            gradient2 = ctx2.createRadialGradient(half, half, 0, half, half, half);
        gradient2.addColorStop(0.025, '#CCC');
        gradient2.addColorStop(0.1, 'hsl(' + hue + ', 61%, 33%)');
        gradient2.addColorStop(0.25, 'hsl(' + hue + ', 64%, 6%)');
        gradient2.addColorStop(1, 'transparent');
        ctx2.fillStyle = gradient2;
        ctx2.beginPath();
        ctx2.arc(half, half, half, 0, Math.PI * 2);
        ctx2.fill();
        // End cache
        function random(min, max) {
            if (arguments.length < 2) {
                max = min;
                min = 0;
            }
            if (min > max) {
                var hold = max;
                max = min;
                min = hold;
            }
            return Math.floor(Math.random() * (max - min + 1)) + min;
        }
        function maxOrbit(x, y) {
            var max = Math.max(x, y),
                diameter = Math.round(Math.sqrt(max * max + max * max));
            return diameter / 2;
            //星星移动范围，值越大范围越小，
        }
        var Star = function () {
            this.orbitRadius = random(maxOrbit(w, h));
            this.radius = random(60, this.orbitRadius) / 8;
            //星星大小
            this.orbitX = w / 2;
            this.orbitY = h / 2;
            this.timePassed = random(0, maxStars);
            this.speed = random(this.orbitRadius) / 50000;
            //星星移动速度
            this.alpha = random(2, 10) / 10;
            count++;
            stars[count] = this;
        }
        Star.prototype.draw = function () {
            var x = Math.sin(this.timePassed) * this.orbitRadius + this.orbitX,
                y = Math.cos(this.timePassed) * this.orbitRadius + this.orbitY,
                twinkle = random(10);
            if (twinkle === 1 && this.alpha > 0) {
                this.alpha -= 0.05;
            } else if (twinkle === 2 && this.alpha < 1) {
                this.alpha += 0.05;
            }
            ctx.globalAlpha = this.alpha;
            ctx.drawImage(canvas2, x - this.radius / 2, y - this.radius / 2, this.radius, this.radius);
            this.timePassed += this.speed;
        }
        for (var i = 0; i < maxStars; i++) {
            new Star();
        }
        function animation() {
            ctx.globalCompositeOperation = 'source-over';
            ctx.globalAlpha = 0.5; //尾巴
            ctx.fillStyle = 'hsla(' + hue + ', 64%, 6%, 2)';
            ctx.fillRect(0, 0, w, h)
            ctx.globalCompositeOperation = 'lighter';
            for (var i = 1, l = stars.length; i < l; i++) {
                stars[i].draw();
            };
            window.requestAnimationFrame(animation);
        }
        animation();
    </script>
</body>

</html>

链接：https://pan.baidu.com/s/1Wwf2Y39YVPcIgArws-_i-g 
提取码：26cq 
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